In a prior art process over which the invention represents an improvement and as described in German patent document DE 16 21 085 A1, a Watts electrolytic bath containing the usual brighteners (basic brighteners) can be used. A Watts electrolyte can be that described in the LPW "Taschenbuch fur Galvanotechnik", Vol. 1, Verfahrenhstechnik, 13, issued 1988, (Pg. 173 to 177), i.e. Handbook for Electroplating, Process Technology. The process of the prior art for the production of glare-free coatings, utilizes substituted and/or unsubstituted ethylene-oxide adducts, propylene-oxide adducts or ethylene-oxide/propylene-oxide adducts with an adduct concentration of 5 to 100 mg/l and a temperature of the bath at 40 to 75.degree. C. The adducts, under the conditions used heretofore formed a finely dispersed emulsion which appeared as cloudiness. The droplets of the emulsion were assumed to be the basis for the glare-free surface. However, the glare-free property can be improved.
The term "glare-free" is used here to characterize a surface of a nickel deposit which provides more or less of a satin-like brightness, i.e. a relatively bright finish but one which does not produce a dazzle effect.
It has been believed heretofore that such a satin-like bright nickel deposit requires the addition to the bath of nonionic surface-active agents which tend to precipitate out at high electrolyte temperatures. In that case, they form an organic contaminant in the electrolyte in the form of an emulsion. Of course not every optionally selectable nonionic surface-active agent can be used since the cloud point, i.e. the electrolyte temperature at which the surface-active agent precipitates, depends upon the chemical structure and the concentrations of the substances in the electrolyte. In addition, the salt contribution of the electrolyte is a determinant of the level of the cloud point. In spite of the more or less fine distribution of the emulsion droplets in this system, there is a danger that the emulsion droplets may ball up to produce relatively large conglomerates which can interfere with the satin-like character of the deposit. As a consequence, it has been necessary in the past to cool the electrolyte in a correspondingly dimensioned bypass circulation so that the cloud point of the nonionic surfactant will not be approached or exceeded and the nonionic surfactants will remain dissolved in the electrolyte. In addition, the electrolyte must be heated to the requisite working temperature. The process must be carried out with considerable care and monitoring to avoid the formation of black pores. Finally, the antiglare effect and the reproducibility are normally not sufficient and reliability of the process cannot be ensured.
It is known to utilize a variety of foreign substances in the electrolyte bath (see DE 23 27 881 C2). These foreign substances can be organic compounds which can react in the electrolyte to form cation-active or amphoteric substances with organic anions. The anion supply substances can include alkylsulfates or sulfonic acids or arylsulfates or sulfonic acid in addition to alkyl or arylsulfates sulfonic acids.
To obtain a brightening effect in conjunction with the antiglare effect, the electrolyte additionally could contain known primary and/or secondary brighteners. These organic compounds provide a decoratively useful antiglare effect in the form of a matte finish for certain production periods. After a certain time interval, however, these foreign substances must be filtered out to avoid agglomeration. This is expensive. As a result of the filtering of the agglomerates and the materials which tend to agglomerate from the solution, during the next working cycle the organic foreign substances must be formed anew which is comparatively expensive.